1.25" Astronomical Telescope Collimation Eyepiece for Refracting Telescopes

Please adjust the screw if it is not in the center, in this way, you will collimate sucessfully. Used to calibrate the optical axis of a refractor, put the collimation eyepiecre into the tube. Make sure the black spot is in the center of 2 lines of collimation eyepiece. A wonderful accessory for both photography and astronomy lovers. 1.25 inch calibration eyepiece is of short size, made of aluminum alloy.